1. Field of the Invention
This invention pertains generally to insect and other pest control treatments and more particularly to methods for rapidly eliminating infestations of insects and other living organisms from commodities using low oxygen atmospheres, pressure differentials and metabolism manipulations with disinfectants, antiseptics, toxics or exposure to intense non-thermal radio frequencies.
2. Description of the Related Art
Every year considerable quantities of pesticides are applied to commodities by producers at various stages of agricultural production, from pre-planting to post harvest, in order to eradicate unwanted insects and other animal, microbial and fungal pests. The presence of egg, larval and adult forms of insects creates the possibility of cross-infestation of commodities and increasing losses during transportation and storage. Established quarantine barriers regulate transportation of agricultural commodities worldwide in order to reduce the potential for propagation and transportation of non-indigenous pests. Many commodities cannot be legally imported or exported to various countries without pesticide treatments to eliminate quarantine pests and to certify that the commodities are free from pests.
Methyl bromide, for example is widely used in the industry as a gaseous fumigant that can disinfest a variety of fresh foods, agricultural soils and structural facilities. However, methyl bromide is scheduled to be banned in the next few years because of the capability of methyl bromide to scavenge ozone in the atmosphere. Agriculture in the United States used about 60 million pounds of methyl bromide before the mandatory reductions began in 1999.
The use of methyl bromide or other chemicals in the fresh fruit industry is often unsatisfactory due to the creation of cosmetic blemishes or a reduction in the effective shelf life of the fruit. In addition, applications of methyl bromide at concentrations sufficient to control pests on stored and exported commodities may produce bromide residue levels that are relatively high.
Likewise, other pesticides known in the art have shown erratic performance at low concentrations and have produced crop damage and unacceptable residue levels in some cases. Other pesticides that are widely used with pre-harvest and post-harvest applications include phosphine, chloropicrin, 1,3-dichloropropene, Telone/Vapam, sulfaryl fluoride and hydrogen cyanide. The use of pesticides in general and these insecticides in particular are of global concern due to the detrimental effects they have on animals, air, water and soil as well as the impact they have on public health and agricultural workers.
Another approach to the eradication of insect infestation in food commodities in the art is the use of thermal energy. However, thermal energy, such as the use of hot water, is unsatisfactory because it can cause rapid deterioration of the commodity and typically uses a large amount of energy. Thermal energy is normally used in the fresh produce industry only when no other alternatives are viable or available.
A further approach to disinfestation has been to expose the commodity to a controlled atmosphere with low oxygen concentrations and increased carbon dioxide concentrations. However, these techniques have been inconsistent and often ineffective for eliminating insects, mites and other pests. Present controlled atmosphere approaches require several days to weeks to conduct and are therefore of limited use in the fresh produce industry. One reason that controlled atmosphere techniques are only marginally effective is that many insects can survive low oxygen or increased carbon dioxide environments by collapsing portions of their respiratory system to form air sacks providing a reserve of oxygen. Such reserves may allow some types of insects to survive for several days or more.
Furthermore, some fresh foods may experience detrimental changes in color, texture, acidity and other characteristics from prolonged exposure to high carbon dioxide environments. Accordingly, controlled atmosphere techniques are not considered viable for disinfestation and quarantine applications with fresh produce.
Additionally, there are major human safety concerns that exist today from the potential contamination of food commodities with pathogenic bacteria such as Escherichia coli O157:H7, Salmonella sp., Listeria, and especially Campylobacter. Each of these pathogenic bacteria has recently been identified as disease causing agents from the consumption of many common food commodities. It is estimated that outbreaks of food borne illnesses in the United States affect 12 million people and result in the death of approximately 4,000 individuals annually. Similarly, the control of protozoa (i.e. Toxoplasma sp., Cryptosporidium sp., and/or Cyclospora sp.) and other parasites on many foods and especially on fresh fruits and vegetables is an important challenge for agricultural producers. For example, humans may become infected with parasites by ingesting tissue cysts from undercooked meat or other infected food or water. Recently, several outbreaks of Cyclospora associated gastroenteritis in humans were linked to the consumption of raspberries, lettuce and basil. There are presently no practical methods available to disinfect foods from infective oocysts.
Microbial activity may also generate a variety of toxins, such as Aflatoxin from Aspergillius flavus in grains, that are detrimental to public health or may otherwise make the commodity lose its value in the marketplace. Agricultural commodities such as fresh produce, grains, seeds, and spices may also be affected by fungal and/or bacterial contaminants. It is therefore desirable to inhibit the presence of disease-carrying organisms within food and agricultural commodities as well as eradicate insect infestations. This can be accomplished by either slowing down the development of spoilage organisms (biostatic effects) or by casing a lethal effect on the organism (biocidal effect).
Accordingly, there is a need for an apparatus and method for eradicating a wide variety of insect and microbial pests that is effective and does not leave toxic residues or alter the characteristics of the commodity that is treated. The present invention satisfies these needs as well as others and generally overcomes the deficiencies in the art.